using Keithley 2400 SourceMeter and either a Keithley 6485 or keithley 487 picoammeterat the same time

[matt_tt]

Hi guys,

I am doing a project whereby i have to collect data from the sourcemeter and picoammeter at the same time. Right now i have the labview IV for sourcemeter, which allows me to collect the current and voltage data. 

My question is, i'm having difficulties for picoammeter labview program and is there any method that i can collect data at the same time through the use of both instruments. 

Both instruments are connected via a GPIB-USB converter and it is connected to my pc. I attached a copy of the labview program for 32400 Sourcemeter.

Thank you.

[Minions]

You will not be able to collect simultaneous data using a single GPIB port.  GPIB uses a handshaking protocol that links the talker and listener together to perform tasks then the controller will release them to search out the next instrument that needs to perform a task.  You might get closer to simultaneous reads by getting a second USB to GPIB port or possibly by using an LXI or serial connection with one of the instruments.

[Curt_C]

Hi,

I don't have anyway to test this, but you could try to setup both instruments to take a measurement, ( setup the 2400 for a sweep and the 6485 for a single reading for example) and then send both devices the 'INIT' command over the GPIB at the same time to trigger the readings. I'm not sure how that's done it LabVIEW but in C# it's done using the Write command with an array of address values.

Curt

[Minions]

Curt_C wrote:

Hi,

I don't have anyway to test this, but you could try to setup both instruments to take a measurement, ( setup the 2400 for a sweep and the 6485 for a single reading for example) and then send both devices the 'INIT' command over the GPIB at the same time to trigger the readings. I'm not sure how that's done it LabVIEW but in C# it's done using the Write command with an array of address values.

Curt

---

It will handle it all sequentially.  The array will be handled one element at a time until all elements have been addressed.

This is a hardware limitation as the GPIB (IEEE-488.2) can only address a single piece of equipment at a time.  The controller will make a connection to one of the addressed pieces of equipment, the equipment will then handle the commands from the controller and respond to any queries, then the controller will close that connection and move on to the next piece of equipment repeating the process.  Depending on the equipment processing time of the controller's command/query it might be able to meet your timing needs by handling these commands sequentially.

To avoid this overhead/bottleneck as one piece of equipment is processing a command/query, a parallel bussing scheme is needed.  One can achieve this by either connecting a second GPIB controller and connect the second piece of equipment to it or by connecting to that second piece of equipment via RS-232 or LXI.

A possible option may be to setup all pieces of equipment to await a single trigger.  The single trigger, depending on the equipment, may be able to be sent over the GPIB bus.  If not, an external trigger will be required.  After the devices have triggered and captured the requested data, then go and retrieve that from the instruments.

[matt_tt]

Hi Minions,

Thanks for the suggestion. I forgot to mention that i am using a adaptor cable with two GPIB at the end to link up both instruments together. One of the end of the cable is connected with a GPIB-USB-HS cable. Through this connection, i was thinking that i can obtain readings from both instruments at the same time.

[matt_tt]

Thanks guys for the help.

But i am still having trouble obtaining a labview program for either a 6485 or 487 picoammeter. Is there any recommendation website that i can find a suitable labview program which can measure the current from an external device.

[matt_tt]

Hi,

I am just wondering is there any VI examples that i can use or could you point me a direction where i can find examples of VI.

Thank you

[matt_tt]

Hi,

i am just wondering is there any where i can find examples of VIs? 

Thank you.

[Curt_C]

Hi,

Search in these forum links. There are some sample VIs.

https://forum.tek.com/viewforum.php?f=13https://forum.tek.com/viewforum.php?

f=41&sid=ede5071064951eedda3dd1eb334ef13b

Curt

[matt_tt]

Hi guys, I am wondering does anyone have IV sweep labview script for KE487 Picoammeter/Sourcemeter or can anyone point me to a direction where i can find the script. Thank you so much. Regard, Matt_tt